Since an organic EL panel has a surface emitting structure and a wide illuminating range, it is widely used from the past as an illumination device. This organic EL panel typically has an organic EL element laminated on a substrate such as a glass substrate, and includes a sealing structure to seal the organic EL element and a power supply structure to supply power to the organic EL element. Further, the organic EL element is made by opposing two electrodes one or both of which have a light transmittance, and laminating a light-emitting layer containing an organic compound between these electrodes.
In an illumination device using an organic EL panel, there are cases where a used organic EL panel is replaced with a new organic EL panel in performing maintenance or the like. In such a case, it is preferable that the organic EL panel can be easily replaced. Therefore, Patent Document 1 discloses a structure capable of replacing a used illumination unit with a new illumination unit.